The use of a polyol in the preparation of polyurethanes by reaction of the polyol with a polyisocyanate in the presence of a catalyst and perhaps other ingredients is well known. Conventional polyols for flexible polyurethane foams are usually made by the reaction of a polyhydric alcohol with an alkylene oxide, usually ethylene oxide and/or propylene oxide, to a molecular weight of about 2,000 to 5,000 and above. These polyols are then reached with polyisocyanate in the presence of water or other blowing agents such as fluorocarbons to obtain polyurethane foams. Polyols have been modified in many ways in attempts to improve the properties of the resulting polyurethane.
For example, elastomeric polytetramethylene ether polyurethane polymers may be made from reactions involving a polytetramethylene ether glycol having a molecular weight of at last 750, an organic diisocyanate and a chain extender containing active hydrogen according to U.S. Pat. No. 2,929,800. The glycol may be added to the diisocyanate to form a prepolymer.
Highly elastic polyurethane foams having a density, sag factor, tensile strength and elongation at break which make them suitable for use in upholstery may be prepared by reacting a poly(alkylene ether) polyol having at least about 10% by weight of primary hydroxyl groups and hydrazine or a hydrazine adduct with an organic polyisocyanate which contains at least about 50% by weight of distilled tolylene diisocyanate, according to U.S. Pat. No. 4,107,102.
U.S. Pat. No. 3,294,751 relates to the preparation of polyurethanes via a modified polyol called a ureido-polyol. These low molecular weight ureido-polyols are formed by the reaction of an organic compound consisting of a hydrocarbon group having less than 10 carbons atoms and at least one isocyanate grop and an alkanolamine. Further, the invention disclosed in U.S. Pat. No. 4,118,376 concerns hydrocurable compositions suitable for use as coatings, adhesives or grouts. The composition contains oxazolidine compounds and free isocyanate groups containing prepolymers where the prepolymers are obtained by the reaction of polyisocyanates with special types of dispersions where the dispersed phase is synthesized in situ in a dispersing media of polyhydroxyl compounds.
Other modified polyols are known in which vinyl monomers such as styrene or acrylonitrile or other materials such as hydrazine hydrate have been included to improve the properties of the polyols and thus, the properties of the resulting foam. However, some of these materials are higly toxic and require, in addition, stripping of unreacted vinyl monomers or water of hydration.
A German process described in Offenlegungsschrift No. 2,110,055 is known for making a polyurethane product whereby a hydroxyl-containing amine is included in the formulation in a one-shot process. That is, the hydroxyl-containing amine is simply included initially with the polyol and the polyisocyanate, and a polyurethane product results. The process does not use a polyurea polymer polyol which is then reacted with a polyisocyanate.
A polymer-modified polyol may be formed by polymerizing an alkanolamine with an organic polyisocyanate in the presence of a polyol as taught by British patent application No. 2,072,204A. The alkanolamine may react polyfunctionally with the polyisocyanate to produce polyaddition products which may constitute a stable dispersion in the polyol. The resulting modified polyol is stated to be particularly useful as a polyol starting material for reaction with a polyisocyanate in the manufacture of polyurethane foam.
Stable dispersions are also revealed in U.S. Pat. No. 4,089,835. Here, the stable dispersions comprise polyureas and/or polyhydrazodicarbonamides as the dispersed phase in a hydroxyl group-containing material selected from the group of polyethers, polyester, polyester amides and polycarbonates. These dispersions may be produced by reacting organic polyisocyanates with polyamides containing primary and/or secondary amino groups and/or hydrazines and/or hydrazines in the hydroxyl-containing material. Another patent relating to stable dispersions is U.S. Pat. No. 4,293,470 which relates to stabilizing polyurea polymer polyols by treating them with a secondary amine.
Similar polymer polyols prepared in the presence of water to reduce viscosity are taught as being useful in high resilience (HR) foams, according to U.S. Pat. No. 4,093,569. In this patent description, low viscosity dispersions are produced by reacting organic polyisocyanates with components having at least one hydroxyl group in the presence of more than 4% by weight of water.
An equilibrium product of two polyols, at least one of which is a polyester polyol, can be accomplished by heating the components at 230.degree. C., in the presence of tetraisopropyl titanate as a catalyst. This equilibrium product is taught by U.S. Pat. No. 3,666,724 as a co-polymer which gives a better resulting foam.
Also of interest is U.S. Pat. No. 4,296,213 which relates to polyurea polymer polyols made by the reaction of a hydroxyl-containing amine, a polyether polyol of about 3,000 to 8,000 molecular weight and an organic polyisocyanate. The hydroxyl-containing amines contemplated therein are described as ranging in molecular weight from about 60 to 200, preferably from about 60 to about 150. It was not realized that higher molecular weight, hydroxyl-containing amines, which also contain aromatic groups, would also give a polymer polyol which would impart enhanced properties to flexible polyurethane foams. Additionally, there is U.S. Pat. No. 4,435,527 which relates to polyester polymer polyols made with polyester polycarbonates and polyurethanes therefrom. The reader may also find of interest U.S. Pat. No. 4,374,209 which teaches a polymer-modified polyol formed by polymerizing an olamine, particularly an alkanolamine, with an organic polyisocyanate in the presence of a polyol. The polyaddition products from this process are said to constitute a stable dispersion in the polyol, and the resulting polymer-modified polyol is particularly useful as a polyol starting material for reaction with a polyisocyanate in the manufacture of polyurethane foam. However, the solids content of these polymer-modified polyols ranged only from about 1 to 35%. It would be desirable if this solids content could be increased. It is also noted that tertiary amines are recommended for use as catalysts in U.S. Pat. No. 4,374,209, while such catalysts are not recommended for use herein.
As mentioned, it would be desirable if polymer polyols could be prepared which would minimize the handling of toxic vinyl monomers, such as by eliminating the stripping of such monomers during the synthesis of the polymer polyols. It would further be desirable if polymer polyols could be made with a high solids content, up to 50 weight percent to provide polyurethane foams with enhanced properties. For example, such foams may have higher load bearing characteristics and may be more stable, but also providing a greater content of open cells.